Amrod and Amras dying at the Havens of Sirion
The Havens of Sirion existed for 68 years, but most of the residents, fleeing from Gondolin and from Doriath, were there for less than thirty. The place was supposed to be a hidden refuge, tucked away from Morgoth and lost in the reeds among the many mouths of the River Sirion (a river so wide that there were few navigable crossings, and they were much further north.) It was growing in prosperity, but that would be from a fairly low point, I don't think it can have been rich or luxurious. The Feanorians were no longer a great army, they must have been a fairly small force by the time they got to Sirion, yet they were able to completely destroy it. Given where the Feanorian power-base was, in the East, in Ossiriand, I don't think they can have attacked on horseback, because they would have to get across the River Sirion to get there, and building horse-transports across the Sirion seems like it would be pretty difficult. So I think they left their horses behind (if they still had horses at that point).
A real-world historical parallel for the Havens of Sirion might be King Alfred's secret base on the Isle of Athelney, when he was fighting the Vikings, and perhaps also the reeds and fens of the Saxon hero Hereward the Wake. So it should not be a great city of stone, but a secret place full of creeks, ferries and bridges, with tree-houses and flets like Lorien, and probably architecture of wildly differing (but all relatively quick to build and simple) styles.
Curufin is the son most like his father, and yet I don't think we are told of any of his creations or ideas. I thought perhaps he invented the process by which Elven swords glow in the presence of orcs and other evil things, since that technology seems to be widespread and very useful in the First Age, so was perhaps invented early on by one of the first Noldor arrivals, maybe in the first Years of the Sun. Perhaps there was originally a companion piece to go with the sword - maybe a shield that tells you which direction the orc is hiding, and that it is an orc and not a Balrog?
Anyway, here is Curufin working on sword-smithing with his son. I have a soft spot for Curufin, despite his behaviour towards poor Finrod. I think that perhaps Curufin communicated fear to the people of Nargothrond so effectively because he was himself secretly terribly afraid and could not admit it. It would be hard to have Maedhros as your big brother, Feanor as your father, and have a son to worry about, and to know that you were afraid and must never show it. He's a maker of things, is Curufin. Perhaps he is cursed with an imagination.
Caranthir's stronghold at the foot of Mount Rerir
Caranthir's people lived in Thargelion, around Lake Helevorn, the deep mountain-shadowed lake at the foot of Mount Rerir towards the northern end of the Ered Luin. Caranthir's stronghold was at the foot of the mountain. I imagine they had boats and went fishing in Lake Helevorn. Here's a view of the stronghold and Mount Rerir, just before dawn. (Sorry, you can't see Caranthir himself. He's probably in bed.)
Huan & Celegorm
Huan is described as a wolfhound of Valinor, and often the assumption when he is drawn (if not rendered simply as a wolf x dog) has tended towards the Irish Wolfhound. But the last wolf in Ireland was killed in 1786. Since then, a giant hairy ‘wolfhound’ dog has been bred, basically to look impressive rather than be functional. People who breed hunting sighthounds (lurchers) do not typically use Irish Wolfhounds when they are choosing breeding stock, because they are too clumsy, too shortlived and generally not very healthy.
Where else do we find wolfhounds? Well, in Russia, where there is a different kind of wolfhound, the borzoi, otherwise known as the Russian Wolfhound, which is a more functional but still giant breed dog with a much more recent working pedigree. These are stunning dogs, often with spectacular golden coats that look as if they are straight from Aman. I feel that the borzoi is a much better fit for Huan’s physical appearance than the Irish Wolfhound.
"Tears unnumbered ye shall shed; and the Valar will fence Valinor against you, and shut you out, so that not even the echo of your lamentation shall pass over the mountains. On the House of Fëanor the wrath of the Valar lieth from the West unto the uttermost East... And those that endure in Middle-earth and come not to Mandos shall grow weary of the world as with a great burden, and shall wane, and become as shadows of regret..." (I think Maglor later found that fading into a shadow of regret took longer than he was expecting.)
Maedhros at Himring
I think there must be terraces on the outside of the hill to help provide some fresh food when under siege (growing something tough and northern: raspberries? Apples? Oats? Actually, it’s probably ‘taters, isn’t it. They use horse manure to warm the soil and a cunning Noldorin fleece protection system to protect from wind and frost. I expect they keep chickens too. ) There's some grazing / horse exercise space inside the walls, as well as lots of underground storage and accommodation. Apparently putting the Star of Fëanor on doors is a tradition.